Aging is associated with alterations in left ventricular (LV) relaxation and compliance, even in the absence of manifest co-morbid conditions such as coronary artery disease or hypertension. This "diastolic dysfunction" may result in an elevation of LV filling pressure and cause signs and symptoms of congestive heart failure (CHF) despite the presence of preserved systolic function. This problem is critical for elderly CHF patients in whom nearly 1/2 may have predominantly diastolic dysfunction as the cause of their heart failure. The broad objective of this proposal is to determine the precise alterations of diastolic function associated with normal, healthy aging in humans, and compare these changes with those associated with CHF due to diastolic dysfunction. The hypotheses to be tested include: 1) Normal aging is associated with alterations in both relaxation and chamber compliance of the LV leading to impaired ventricular filling compared to healthy young adults. Moreover, such abnormalities will be substantially reduced in fit compared to sedentary healthy elderly subjects; 2) Patients with CHF and preserved LV systolic function have more pronounced abnormalities of LV chamber compliance and relaxation which contribute to the development of CHF; 3) Exercise training in both the healthy aged, as well as patients with CHF and diastolic dysfunction will improve abnormalities of diastolic function and will be an effective therapy for this disease. To test these hypotheses, we propose to accomplish the following specific aims: a) To measure the static component of diastole directly by constructing ventricular function (Starling) and LV pressure/volume curves in well, sedentary and fit elderly adults. The dynamic component of diastole will be assessed using state- of-the-art imaging techniques including: tissue Doppler imaging; color Doppler M-mode echo; and magnetic resonance imaging with myocardial tagging. b) To select a group of patients with CHF but preserved systolic function, and to quantify left ventricular relaxation and compliance using the same methods; c) To repeat the specific measures of diastolic function after a prolonged (one year) endurance exercise training program in both the sedentary elderly, and patients with CHF and diastolic dysfunction. These studies will result in a comprehensive understanding of the effect of normal aging and physical conditioning on LV diastolic function, and will identify the specific abnormalities of diastole which lead to CHF in the absence of contractile dysfunction. The precise dose of exercise necessary to restore normal diastolic function will be identified and will allow specific exercise prescription for these populations.